College Physics
1st Edition
ISBN: 9781938168000
Author: Paul Peter Urone, Roger Hinrichs
Publisher: OpenStax College
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Chapter 9, Problem 18PE
In Figure 9.21, the cg of the pole held by the pole vaulter is 2.00 m from the left hand, and the hands are 0.700 m apart. Calculate the force exerted by (a) his right hand and (b) his left hand. (c) If each hand supports half the weight of the pole in Figure 9.19, show that the second condition for equilibrium (net
Figure 9.21 A pole vaulter is holding a pole horizontally with both hands. The center of gravity is to the left side of the vaulter.
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Why is the following situation impossible? A uniform beam of mass mb = 3.00 kg and length ℓ = 1.00 m supports blocks with masses m1 = 5.00 kg and m2 = 15.0 kg at two positions as shown. The beam rests on two triangular blocks, with point P a distance d = 0.300 m to the right of the center of gravity of the beam. The position of the object of mass m2 is adjusted along the length of the beam until the normal force on the beam at O is zero.
A uniform beam resting on two pivots has a length L = 6.00 m and mass M = 90.0 kg. The pivot under the left end exerts a normal force η1 on the beam, and the second pivot located a distance ℓ = 4.00 m from the left end exerts a normal force η2. A woman of mass m = 55.0 kg steps onto the left end of the beam and begins walking to the right as shown. The goal is to find the woman’s position when the beam begins to tip. (a) What is the appropriate analysis model for the beam before it begins to tip? (b) Sketch a force diagram for the beam, labeling the gravitational and normal forcesacting on the beam and placing the woman a distance x to the right of the first pivot, which is the origin. (c) Where is the woman when the normal force η1 is the greatest? (d) What is η1 when the beam is about to tip? (e) Use as shown to find the value of η2 when the beam is about to tip.(f) Using the result of part (d) and as shown, with torques computed around the second pivot, find the woman’s position x…
In unit-vector notation, what is the torque about the origin on a jar of jalapeno peppers located at coordinates (3.0 m, -2.0 m, 4.0 m) due to force F→1 = (9.7 N) î - (4.8 N) ĵ + (5.3 N) k̂ ((a), (b) and (c) for î , ĵ and k̂ components respectively), force F→2 = (-9.7 N) î - (4.8 N) ĵ - (5.3 N) k̂ ((d), (e) and (f) for î , ĵ and k̂ components respectively), and the vector sum of F→1 and F→2 ((g), (h) and (i) for î , ĵ and k̂ components respectively)? Repeat previous part for the torque about the point with coordinates (3.0 m, 2.0 m, 4.0 m) ((j), (k) and (l) for î , ĵ and k̂ components respectively).
Chapter 9 Solutions
College Physics
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